Common braking systems employ the frictional contact, between a drum or disc which rotates with the wheel and a brake shoe or pad carried by the axle, to slow rotation of the wheel. This frictional engagement generates heat which increases the temperatures of the components. These braking systems are normally limited because more heat is collected than is dissipated resulting in the temperature rising to levels at which the components are unable to maintain their braking functions.
An electro-rheological fluid is a fluid the viscosity of which changes in response to the application of an electric field. More specifically, such a fluid has the property of becoming relatively rigid upon application of the field having a component normal to the flow direction prior to application of the field. Such fluids and their applications in clutch devices are disclosed in U.S. Pat. Nos. 2,417,850 and 2,661,596 to Winslow. Such a fluid can be a slurry of fine hydrophilic solids in a hydrophobic liquid. The detailed operation of such fluid in a viscous shear clutch is disclosed in U.S. Pat. No. 4,444,298.
One proposed braking system includes a set of rotor plates interdigitated with a set of stator plates, and with a magnetic brake fluid disposed between the sets of plates. The magnetic brake fluid is a slurry or mixture of magnetic particles and a liquid such as oil. The braking system includes a radiator for cooling the brake fluid. For further information regarding the structure and operation of such a braking system, reference may be made to U.S. Pat. No. 2,690,241.